Synthetic polymer materials such as hydrophobic polymers (polyvinyl chloride, polystyrene, silicone resin, polymethacrylic acid ester, fluororesin, etc.) and hydrophilic polymers (polyvinyl alcohol, poly (2-hydroxyethyl methacrylate), polyacrylamide, etc.), etc. are widely used as medical polymer materials. For example, medical devices, such as cell culture vessels, catheters or artificial organs are known wherein such synthetic polymer materials are used as medical polymer materials.
However, the above synthetic polymer materials are insufficient in biocompatibility. That is, a protein such as fibrinogen, immunoglobulin G (IgG), insulin, histone, carbonic anhydrase, etc. is likely to be easily adsorbed on the device surface. Once the protein is adsorbed on the device surface, further cells (blood cells, platelets, etc.) are likely to adhere at that portion. Therefore, adverse effects on the living body such as thrombus formation, inflammatory reaction, etc. or problems such as deterioration of the device are likely to be brought about.
Therefore, in the medical device using a synthetic polymer material, it has been attempted to improve the biocompatibility by forming, on its surface, a coating layer made of a synthetic polymer material such as a polymer of 2-methacryloyloxyethyl phosphorylcholine having a structure similar to a biological membrane, or a polymer containing polyoxyethylene glycol (e.g. Non-Patent Document 1).
However, the above synthetic polymer material is water soluble, and therefore, if the coating layer is formed by the synthetic polymer material alone, the synthetic polymer material tends to elute from the coating layer during use of the device, and the biocompatibility tends to be reduced. Therefore, it has been proposed to increase the water resistance e.g. by copolymerizing the above 2-methacryloyloxyethyl phosphorylcholine with a hydrophobic monomer such as butyl methacrylate (Patent Document 1), by reacting a prepolymer having a hydroxy group and a phospholipid-like structure with a diisocyanate compound thereby to crosslink them by a urethane bond (Patent Document 2), or by fixing a hydrophilic polymer obtained by copolymerizing an epoxy group-containing monomer, on the surface of a material by the reaction of epoxy groups (Patent Document 3).